The trends and prevalence of obesity and morbid obesity among Australian school-aged children, 1985-2014

Abstract

Aim: Children with obesity have a greater risk of adverse social and physical health outcomes. We examined temporal changes in body mass index (BMI) z-scores and the prevalence obesity and morbid obesity in children from 1985 to 2014.

Methods: Secondary data analysis of BMI data for children aged 7-15 years from five cross-sectional Australian datasets. Changes in age- and gender-adjusted BMI (BMI z-scores) and nutritional status were categorised using the International Obesity Task Force cut-off points.

Results: The percentage of children who were obese tripled between 1985 and 1995 from 1.6 to 4.7%, before plateauing between 1995 and 2014. The percentage of morbidly obese children was <1% in 1985 and 1995, increasing to 2% between 1995 and 2007, with no further increase between 2007 and 2014. The proportion of obese children classified as morbidly obese was 12% in 1985-1995, 24% in 2007-2012 and 28% in 2014. Between 1985 and 2012, the mean BMI z-score increased in children categorised as obese from 1.94 (standard deviation 0.15) to 2.03 (0.22), and then plateaued. For morbidly obese children, the mean BMI z-score was 2.4 (0.13) and remained similar over the study period.

Conclusions: Our findings suggest that the relative fatness of children with morbid obesity, as measured by BMI z-score, has remained stable. The proportion of obese and morbidly obese children has also plateaued between 2007 and 2014. However, the prevalence of obesity remains high, and more dedicated resources are required to treat children with obesity to reduce the short- and long-term health impact.

Keywords: body mass index z-score; morbid obesity; obesity; prevalence.